/***
 * ASM: a very small and fast Java bytecode manipulation framework Copyright (c) 2000-2011 INRIA,
 * France Telecom All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met: 1. Redistributions of source code must retain the
 * above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions
 * in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.googlecode.aviator.asm;

/**
 * A visitor to visit a Java class. The methods of this class must be called in the following order:
 * <tt>visit</tt> [ <tt>visitSource</tt> ] [ <tt>visitOuterClass</tt> ] ( <tt>visitAnnotation</tt> |
 * <tt>visitAttribute</tt> )* ( <tt>visitInnerClass</tt> | <tt>visitField</tt> |
 * <tt>visitMethod</tt> )* <tt>visitEnd</tt>.
 *
 * @author Eric Bruneton
 */
public abstract class ClassVisitor {

  /**
   * The ASM API version implemented by this visitor. The value of this field must be one of
   * {@link Opcodes#ASM4}.
   */
  protected final int api;

  /**
   * The class visitor to which this visitor must delegate method calls. May be null.
   */
  protected ClassVisitor cv;

  /**
   * Constructs a new {@link ClassVisitor}.
   *
   * @param api the ASM API version implemented by this visitor. Must be one of
   *        {@link Opcodes#ASM4}.
   */
  public ClassVisitor(final int api) {
    this(api, null);
  }

  /**
   * Constructs a new {@link ClassVisitor}.
   *
   * @param api the ASM API version implemented by this visitor. Must be one of
   *        {@link Opcodes#ASM4}.
   * @param cv the class visitor to which this visitor must delegate method calls. May be null.
   */
  public ClassVisitor(final int api, final ClassVisitor cv) {
    if (api != Opcodes.ASM4) {
      throw new IllegalArgumentException();
    }
    this.api = api;
    this.cv = cv;
  }

  /**
   * Visits the header of the class.
   *
   * @param version the class version.
   * @param access the class's access flags (see {@link Opcodes}). This parameter also indicates if
   *        the class is deprecated.
   * @param name the internal name of the class (see {@link Type#getInternalName()
   *        getInternalName}).
   * @param signature the signature of this class. May be <tt>null</tt> if the class is not a
   *        generic one, and does not extend or implement generic classes or interfaces.
   * @param superName the internal of name of the super class (see {@link Type#getInternalName()
   *        getInternalName}). For interfaces, the super class is {@link Object}. May be
   *        <tt>null</tt>, but only for the {@link Object} class.
   * @param interfaces the internal names of the class's interfaces (see
   *        {@link Type#getInternalName() getInternalName}). May be <tt>null</tt>.
   */
  public void visit(int version, int access, String name, String signature, String superName,
      String[] interfaces) {
    if (cv != null) {
      cv.visit(version, access, name, signature, superName, interfaces);
    }
  }

  /**
   * Visits the source of the class.
   *
   * @param source the name of the source file from which the class was compiled. May be
   *        <tt>null</tt>.
   * @param debug additional debug information to compute the correspondance between source and
   *        compiled elements of the class. May be <tt>null</tt>.
   */
  public void visitSource(String source, String debug) {
    if (cv != null) {
      cv.visitSource(source, debug);
    }
  }

  /**
   * Visits the enclosing class of the class. This method must be called only if the class has an
   * enclosing class.
   *
   * @param owner internal name of the enclosing class of the class.
   * @param name the name of the method that contains the class, or <tt>null</tt> if the class is
   *        not enclosed in a method of its enclosing class.
   * @param desc the descriptor of the method that contains the class, or <tt>null</tt> if the class
   *        is not enclosed in a method of its enclosing class.
   */
  public void visitOuterClass(String owner, String name, String desc) {
    if (cv != null) {
      cv.visitOuterClass(owner, name, desc);
    }
  }

  /**
   * Visits an annotation of the class.
   *
   * @param desc the class descriptor of the annotation class.
   * @param visible <tt>true</tt> if the annotation is visible at runtime.
   * @return a visitor to visit the annotation values, or <tt>null</tt> if this visitor is not
   *         interested in visiting this annotation.
   */
  public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
    if (cv != null) {
      return cv.visitAnnotation(desc, visible);
    }
    return null;
  }

  /**
   * Visits a non standard attribute of the class.
   *
   * @param attr an attribute.
   */
  public void visitAttribute(Attribute attr) {
    if (cv != null) {
      cv.visitAttribute(attr);
    }
  }

  /**
   * Visits information about an inner class. This inner class is not necessarily a member of the
   * class being visited.
   *
   * @param name the internal name of an inner class (see {@link Type#getInternalName()
   *        getInternalName}).
   * @param outerName the internal name of the class to which the inner class belongs (see
   *        {@link Type#getInternalName() getInternalName}). May be <tt>null</tt> for not member
   *        classes.
   * @param innerName the (simple) name of the inner class inside its enclosing class. May be
   *        <tt>null</tt> for anonymous inner classes.
   * @param access the access flags of the inner class as originally declared in the enclosing
   *        class.
   */
  public void visitInnerClass(String name, String outerName, String innerName, int access) {
    if (cv != null) {
      cv.visitInnerClass(name, outerName, innerName, access);
    }
  }

  /**
   * Visits a field of the class.
   *
   * @param access the field's access flags (see {@link Opcodes}). This parameter also indicates if
   *        the field is synthetic and/or deprecated.
   * @param name the field's name.
   * @param desc the field's descriptor (see {@link Type Type}).
   * @param signature the field's signature. May be <tt>null</tt> if the field's type does not use
   *        generic types.
   * @param value the field's initial value. This parameter, which may be <tt>null</tt> if the field
   *        does not have an initial value, must be an {@link Integer}, a {@link Float}, a
   *        {@link Long}, a {@link Double} or a {@link String} (for <tt>int</tt>, <tt>float</tt>,
   *        <tt>long</tt> or <tt>String</tt> fields respectively). <i>This parameter is only used
   *        for static fields</i>. Its value is ignored for non static fields, which must be
   *        initialized through bytecode instructions in constructors or methods.
   * @return a visitor to visit field annotations and attributes, or <tt>null</tt> if this class
   *         visitor is not interested in visiting these annotations and attributes.
   */
  public FieldVisitor visitField(int access, String name, String desc, String signature,
      Object value) {
    if (cv != null) {
      return cv.visitField(access, name, desc, signature, value);
    }
    return null;
  }

  /**
   * Visits a method of the class. This method <i>must</i> return a new {@link MethodVisitor}
   * instance (or <tt>null</tt>) each time it is called, i.e., it should not return a previously
   * returned visitor.
   *
   * @param access the method's access flags (see {@link Opcodes}). This parameter also indicates if
   *        the method is synthetic and/or deprecated.
   * @param name the method's name.
   * @param desc the method's descriptor (see {@link Type Type}).
   * @param signature the method's signature. May be <tt>null</tt> if the method parameters, return
   *        type and exceptions do not use generic types.
   * @param exceptions the internal names of the method's exception classes (see
   *        {@link Type#getInternalName() getInternalName}). May be <tt>null</tt>.
   * @return an object to visit the byte code of the method, or <tt>null</tt> if this class visitor
   *         is not interested in visiting the code of this method.
   */
  public MethodVisitor visitMethod(int access, String name, String desc, String signature,
      String[] exceptions) {
    if (cv != null) {
      return cv.visitMethod(access, name, desc, signature, exceptions);
    }
    return null;
  }

  /**
   * Visits the end of the class. This method, which is the last one to be called, is used to inform
   * the visitor that all the fields and methods of the class have been visited.
   */
  public void visitEnd() {
    if (cv != null) {
      cv.visitEnd();
    }
  }
}
